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Evidence for frequency-dependent arterial damage in vibrated rat tails.

Authors
Curry-BD; Govindaraju-SR; Bain-JL; Zhang-LL; Yan-JG; Matloub-HS; Riley-DA
Source
Anat Rec Part A Discov Mol Cell Evol Biol 2005 Jun; 284(2):511-521
NIOSHTIC No.
20028792
Abstract
The effects of single 4-hr bouts of continuous 30, 60, 120, and 800 Hz tail vibration (49 m/sec2, root mean squared) were compared to assess frequency-amplitude-related structural damage of the ventral caudal artery. Amplitudes were 3.9, 0.98, 0.24, and 0.0055 mm, respectively. Vibrated, sham-vibrated, and normal arteries were processed for light and electron microscopy. The Curry rat tail model of hand-arm vibration (Curry et al. Muscle Nerve 2002;25:527-534) proved well-suited for testing multiple frequencies. NFATc3 immunostaining, an early marker of cell damage, increased in smooth muscle and endothelial cells after 30, 60, and 120 Hz but not 800 Hz. Increased vacuolization, which is indicative of smooth muscle contraction, occurred for all frequencies except 800 Hz. Vacuoles increased in both endothelial and smooth muscle cells after 60 and 120 Hz. Only 30 Hz showed pronounced smooth muscle cell vacuolization along the internal and external elastic membranes, suggesting stretch-mediated contraction from the large amplitude shear stress. Discontinuities in toluidine blue staining of the internal elastic membrane (IEM) increased for all frequencies, indicating vibration-induced structural weakening of this structure. Patches of missing IEM and overlying endothelium occurred in approximately 5% of arteries after 60, 120, and 800 Hz. The pattern of damage after 800 Hz suggests that the IEM is disrupted because it resonates at this frequency. Vibration acceleration stress and smooth muscle contraction appear to be the major contributors to arterial damage. The pattern of vibration-induced arterial damage of smooth muscle and endothelial cells is frequency-amplitude-dependent.
Keywords
Hand-injuries; Arm-injuries; Vibration; Laboratory-animals; Animals; Animal-studies; Exposure-levels; Exposure-assessment; Vibration-effects; Vibration-exposure; Neurovascular-disorders
Contact
Danny A. Riley, Department of Cell Biology, Neurobiology and Anatomy, 8701 Watertown Plank Road, Medical College of Wisconsin, Milwaukee, WI 53226
Publication Date
20050601
Document Type
Journal Article
Email Address
dariley@mcw.edu
Funding Amount
922402
Funding Type
Grant
Fiscal Year
2005
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-R01-OH-003493
Issue of Publication
2
ISSN
1552-4884
Priority Area
Other Occupational Concerns
Source Name
The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology
State
WI
Performing Organization
Medical College of Wisconsin, Milwaukee, Wisconsin
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